Design and Fabrication of a Geo Probe for Determining the qu/su of Soft Soil

Joseph Ling, Chai Teck Jung, Sam Toong Hai, Lee Yee Loon, Abdul Hameed Memon


Aim of Study

This study is to design and fabricate a geo probe that is used to determine the basic properties of soft soil.

Need of Study

Deep foundation on soft is difficult as it is vulnerable to lateral movement when it is subjected to vertical load. Due to this problem, a geo probe is designed and constructed with foam concrete to determine the condition of the soil which is based on the ultimate bearing capacity, qu and the undrained shear strength, Su.

Research Approach

Designed geo probe comprises a cylindrical hollow PVC pipe of 50mm for internal diameter and 100mm for the external diameter in filled with foamed concrete of 1200kg/m3 density. It was installed on a test site in RECESS and loaded to compute the value of ratio ultimate bearing capacity over undrained shear strength in the particular study of soil. As commonly said ultimate bearing capacity is more than undrained shear strength by five times which only happen in a certain condition.

Research Findings

This study formed a basis design of a geo probe which can be used to determine basic properties of soft soil. Experimental work showed that at shear strength of 1kpa the ratio of qu/Su is 6.7 and at 19kpa, the ratio of qu/Su is 3.1.


This study is to evaluate and design a scale model to be tested under static loading on soft soil. The study will cover the experimentation of the scaled down the probe for field trials in UTHM at the soft soils that are located at RECESS. It will also consist of determining the ratio of qu/Su from the results that have been obtained from the experiment.  

Importance and Contribution

The result of this study is expected to improve the understanding on the methods of determining the bearing capacity and the ratio of qu/Su of soft soil. 

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